diff --git a/src/frontend/pp.cpp b/src/frontend/pp.cpp
index 250d575d2..a281e75aa 100644
--- a/src/frontend/pp.cpp
+++ b/src/frontend/pp.cpp
@@ -403,7 +403,7 @@ struct pp_fn {
             format body_sep;
             if (B) {
                 format B_f = pp(B, 0).first;
-                body_sep = format{space(), colon(), space(), B_f, space(), format(":=")};
+                body_sep = format{space(), colon(), space(), B_f, space(), highlight_keyword(format(":="))};
             } else {
                 body_sep = comma();
             }
diff --git a/src/kernel/expr_formatter.cpp b/src/kernel/expr_formatter.cpp
index c257c22fc..fba1d8bcc 100644
--- a/src/kernel/expr_formatter.cpp
+++ b/src/kernel/expr_formatter.cpp
@@ -11,7 +11,7 @@ namespace lean {
 
 format expr_formatter::operator()(char const * kwd, name const & n, expr const & t, expr const & v) {
     format def = format{highlight_command(format(kwd)), space(), format(n), space(), colon(), space(),
-                        operator()(t), format(" :="), line(), operator()(v)};
+                        operator()(t), space(), highlight_keyword(format(":=")), line(), operator()(v)};
     return group(nest(def));
 }